@article{HajAyedKustererFunkeetal.2015, author = {Haj Ayed, A. and Kusterer, K. and Funke, Harald and Keinz, Jan and Striegan, Constantin and Bohn, D.}, title = {Improvement study for the dry-low-NOx hydrogen micromix combustion technology}, series = {Propulsion and power research}, volume = {Vol. 4}, journal = {Propulsion and power research}, number = {Iss. 3}, issn = {2212-540X}, doi = {10.1016/j.jppr.2015.07.003}, pages = {132 -- 140}, year = {2015}, language = {en} } @article{HoevelerJanserBindewaldetal.2015, author = {Hoeveler, Bastian and Janser, Frank and Bindewald, Thorsten and Gebhardt, Andreas}, title = {Entwurf, Fertigung und Untersuchung eines Windkanalmodells eines innovativen, senkrechtstartenden Kleinflugzeuges}, series = {RTejournal - Forum f{\"u}r Rapid Technologie}, journal = {RTejournal - Forum f{\"u}r Rapid Technologie}, number = {12}, publisher = {Fachhochschule Aachen}, address = {Aachen}, issn = {1614-0923}, url = {http://nbn-resolving.de/urn:nbn:de:0009-2-42921}, pages = {1 -- 5}, year = {2015}, language = {de} } @article{GrundmannDachwaldGrimmetal.2015, author = {Grundmann, Jan Thimo and Dachwald, Bernd and Grimm, Christian D. and Kahle, Ralph and Koch, Aaron Dexter and Krause, Christian and Lange, Caroline and Quantius, Dominik and Ulamec, Stephan}, title = {Spacecraft for Hypervelocity Impact Research - An Overview of Capabilities, Constraints and the Challenges of Getting There}, series = {Procedia Engineering}, volume = {Vol. 103}, journal = {Procedia Engineering}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2015.04.021}, pages = {151 -- 158}, year = {2015}, language = {en} } @article{KonstantinidisFloresMartinezDachwaldetal.2015, author = {Konstantinidis, Konstantinos and Flores Martinez, Claudio and Dachwald, Bernd and Ohndorf, Andreas and Dykta, Paul and Bowitz, Pascal and Rudolph, Martin and Digel, Ilya and Kowalski, Julia and Voigt, Konstantin and F{\"o}rstner, Roger}, title = {A lander mission to probe subglacial water on Saturn's moon enceladus for life}, series = {Acta astronautica}, volume = {Vol. 106}, journal = {Acta astronautica}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-2030 (E-Journal); 0094-5765 (Print)}, pages = {63 -- 89}, year = {2015}, language = {en} } @article{SeifarthGossmannGrosseetal.2015, author = {Seifarth, Volker and Goßmann, Matthias and Grosse, J. O. and Becker, C. and Heschel, I. and Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l}, title = {Development of a Bioreactor to Culture Tissue Engineered Ureters Based on the Application of Tubular OPTIMAIX 3D Scaffolds}, series = {Urologia Internationalis}, volume = {2015}, journal = {Urologia Internationalis}, number = {95}, publisher = {Karger}, address = {Basel}, issn = {0042-1138}, doi = {10.1159/000368419}, pages = {106 -- 113}, year = {2015}, language = {en} } @article{SchuellerKowalskiRaback2016, author = {Sch{\"u}ller, K. and Kowalski, Julia and Raback, P.}, title = {Curvilinear melting - A preliminary experimental and numerical study}, series = {International Journal of Heat and Mass Transfer}, journal = {International Journal of Heat and Mass Transfer}, number = {92}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2015.09.046}, pages = {884 -- 892}, year = {2016}, abstract = {When exploring glacier ice it is often necessary to take samples or implement sensors at a certain depth underneath the glacier surface. One way of doing this is by using heated melting probes. In their common form these devices experience a straight one-dimensional downwards motion and can be modeled by standard close-contact melting theory. A recently developed melting probe however, the IceMole, achieves maneuverability by simultaneously applying a surface temperature gradient to induce a change in melting direction and controlling the effective contact-force by means of an ice screw to stabilize its change in attitude. A modeling framework for forced curvilinear melting does not exist so far and will be the content of this paper. At first, we will extend the existing theory for quasi-stationary close-contact melting to curved trajectories. We do this by introducing a rotational mode. This additional unknown in the system implies yet the need for another model closure. Within this new framework we will focus on the effect of a variable contact-force as well as different surface temperature profiles. In order to solve for melting velocity and curvature of the melting path we present both an inverse solution strategy for the analytical model, and a more general finite element framework implemented into the open source software package ELMER. Model results are discussed and compared to experimental data conducted in laboratory tests.}, language = {de} } @article{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Braun, Carsten and Orifici, Adrian C.}, title = {Operational Modal Analysis of a wing excited by transonic flow}, series = {Aerospace Science and Technology}, volume = {49}, journal = {Aerospace Science and Technology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1270-9638}, doi = {10.1016/j.ast.2015.11.032}, pages = {73 -- 79}, year = {2016}, abstract = {Operational Modal Analysis (OMA) is a promising candidate for flutter testing and Structural Health Monitoring (SHM) of aircraft wings that are passively excited by wind loads. However, no studies have been published where OMA is tested in transonic flows, which is the dominant condition for large civil aircraft and is characterized by complex and unique aerodynamic phenomena. We use data from the HIRENASD large-scale wind tunnel experiment to automatically extract modal parameters from an ambiently excited wing operated in the transonic regime using two OMA methods: Stochastic Subspace Identification (SSI) and Frequency Domain Decomposition (FDD). The system response is evaluated based on accelerometer measurements. The excitation is investigated from surface pressure measurements. The forcing function is shown to be non-white, non-stationary and contaminated by narrow-banded transonic disturbances. All these properties violate fundamental OMA assumptions about the forcing function. Despite this, all physical modes in the investigated frequency range were successfully identified, and in addition transonic pressure waves were identified as physical modes as well. The SSI method showed superior identification capabilities for the investigated case. The investigation shows that complex transonic flows can interfere with OMA. This can make existing approaches for modal tracking unsuitable for their application to aircraft wings operated in the transonic flight regime. Approaches to separate the true physical modes from the transonic disturbances are discussed.}, language = {en} } @article{KowalskiLinderZierkeetal.2016, author = {Kowalski, Julia and Linder, Peter and Zierke, S. and Wulfen, B. van and Clemens, J. and Konstantinidis, K. and Ameres, G. and Hoffmann, R. and Mikucki, J. and Tulaczyk, S. and Funke, O. and Blandfort, D. and Espe, Clemens and Feldmann, Marco and Francke, Gero and Hiecker, S. and Plescher, Engelbert and Sch{\"o}ngarth, Sarah and Dachwald, Bernd and Digel, Ilya and Artmann, Gerhard and Eliseev, D. and Heinen, D. and Scholz, F. and Wiebusch, C. and Macht, S. and Bestmann, U. and Reineking, T. and Zetzsche, C. and Schill, K. and F{\"o}rstner, R. and Niedermeier, H. and Szumski, A. and Eissfeller, B. and Naumann, U. and Helbing, K.}, title = {Navigation technology for exploration of glacier ice with maneuverable melting probes}, series = {Cold Regions Science and Technology}, journal = {Cold Regions Science and Technology}, number = {123}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0165-232X}, doi = {10.1016/j.coldregions.2015.11.006}, pages = {53 -- 70}, year = {2016}, abstract = {The Saturnian moon Enceladus with its extensive water bodies underneath a thick ice sheet cover is a potential candidate for extraterrestrial life. Direct exploration of such extraterrestrial aquatic ecosystems requires advanced access and sampling technologies with a high level of autonomy. A new technological approach has been developed as part of the collaborative research project Enceladus Explorer (EnEx). The concept is based upon a minimally invasive melting probe called the IceMole. The force-regulated, heater-controlled IceMole is able to travel along a curved trajectory as well as upwards. Hence, it allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. The development of such a navigational system has been the focal part of the EnEx project. The original IceMole has been further developed to include relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection integrated through a high-level sensor fusion. This paper describes the EnEx technology and discusses implications for an actual extraterrestrial mission concept.}, language = {en} } @article{BillerbeckBarnatKnutzen2016, author = {Billerbeck, Katrin and Barnat, Miriam and Knutzen, S{\"o}nke}, title = {Kompetenzorientierung auf dem Pr{\"u}fstand. Erprobung von Indikatoren f{\"u}r den Kulturwandel}, series = {Die Hochschullehre}, volume = {2016}, journal = {Die Hochschullehre}, number = {16}, publisher = {WBV Media}, address = {Bielefeld}, issn = {2199-8825}, doi = {10.3278/HSL1616W}, pages = {16}, year = {2016}, abstract = {Der Beitrag fokussiert die Frage nach dem Stand des durch die Bologna-Reform angestoßenen Kulturwandels im Hinblick auf Kompetenzorientierung am Beispiel der Technischen Universit{\"a}t Hamburg (TUHH). An der TUHH wird bereits seit einigen Jahren daran gearbeitet, die Lehre grundlegend neu auszurichten. Hierf{\"u}r setzt das hochschuldidaktische "Zentrum f{\"u}r Lehre und Lernen" (ZLL) verschiedene Maßnahmen ein, wie z.B. eine finanzielle und didaktische Unterst{\"u}tzung von Lehrenden bei der Umstellung ihrer Veranstaltungen, Weiterqualifizierungsangebote und Informationsmaterial. Die Maßnahmen ebenso wie die innovierten Veranstaltungen werden von Lehrenden und Studierenden gut evaluiert. Nach dem Ansatz des Constructive Alignments l{\"a}sst sich jedoch davon ausgehen, dass der Bereich der Pr{\"u}fungen f{\"u}r eine Einsch{\"a}tzung des Status Quo der Kompetenzorientierung besonders relevant ist. Dieser wird deshalb anhand der beiden Kriterien Pr{\"u}fungsformate und Schwierigkeitsstufen von Pr{\"u}fungsaufgaben n{\"a}her beleuchtet, die eng mit der Kompetenzorientierung zusammen h{\"a}ngen. Ergebnisse hierzu aus einer universit{\"a}tsweiten Datenbank zur Studienorganisation sowie aus einer Online-Umfrage unter Studierenden weisen darauf hin, dass das Pr{\"u}fungsformat "Klausur" nach wie vor am st{\"a}rksten verbreitet ist; zugleich sind die Studierenden nach einer Selbsteinsch{\"a}tzung in Pr{\"u}fungen vorrangig mit Aufgaben auf den Taxonomieniveaus "Wiedergeben" und "Anwenden" konfrontiert. Dies l{\"a}sst sich als Hinweis darauf interpretieren, dass es im Hinblick auf eine Kompetenzorientierung in den Pr{\"u}fungen noch weiteren Ver{\"a}nderungsbedarf gibt.}, language = {de} } @article{WeberArentMuenchetal.2016, author = {Weber, Tobias and Arent, Jan-Christoph and M{\"u}nch, Lukas and Duhovic, Miro and Balvers, Johannes M.}, title = {A fast method for the generation of boundary conditions for thermal autoclave simulation}, series = {Composites Part A}, volume = {88}, journal = {Composites Part A}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1359-835X}, doi = {10.1016/j.compositesa.2016.05.036}, pages = {216 -- 225}, year = {2016}, abstract = {Manufacturing process simulation enables the evaluation and improvement of autoclave mold concepts early in the design phase. To achieve a high part quality at low cycle times, the thermal behavior of the autoclave mold can be investigated by means of simulations. Most challenging for such a simulation is the generation of necessary boundary conditions. Heat-up and temperature distribution in an autoclave mold are governed by flow phenomena, tooling material and shape, position within the autoclave, and the chosen autoclave cycle. This paper identifies and summarizes the most important factors influencing mold heat-up and how they can be introduced into a thermal simulation. Thermal measurements are used to quantify the impact of the various parameters. Finally, the gained knowledge is applied to develop a semi-empirical approach for boundary condition estimation that enables a simple and fast thermal simulation of the autoclave curing process with reasonably high accuracy for tooling optimization.}, language = {en} } @article{FunkeKeinzKustereretal.2016, author = {Funke, Harald and Keinz, Jan and Kusterer, Karsten and Ayed, Anis Haj and Kazari, Masahide and Kitajima, Junichi and Horikawa, Atsushi and Okada, Kunio}, title = {Experimental and Numerical Study on Optimizing the Dry Low NOₓ Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {9}, journal = {Journal of Thermal Science and Engineering Applications}, number = {2}, publisher = {ASME}, address = {New York, NY}, issn = {1948-5093}, doi = {10.1115/1.4034849}, pages = {021001 -- 021001-10}, year = {2016}, abstract = {Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low-emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to dry low NOₓ (DLN) hydrogen combustion. The DLN micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOₓ emissions. This combustion principle for air-breathing engines is based on crossflow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flashback and with low NOₓ emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high-thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high-energy injectors, while the DLN micromix characteristics of the design point, under part-load conditions, and under off-design operation are maintained. Atmospheric test rig data on NOₓ emissions, optical flame-structure, and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized micromix flamelets is particularly investigated numerically for the resulting flow field, the flame-structure, and NOₓ formation.}, language = {en} } @article{AyedKustererFunkeetal.2016, author = {Ayed, Anis Haj and Kusterer, Karsten and Funke, Harald and Keinz, Jan}, title = {CFD Based Improvement of the DLN Hydrogen Micromix Combustion Technology at Increased Energy Densities}, series = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)}, volume = {26}, journal = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)}, number = {3}, publisher = {GSSRR}, issn = {2313-4402}, pages = {290 -- 303}, year = {2016}, abstract = {Combined with the use of renewable energy sources for its production, Hydrogen represents a possible alternative gas turbine fuel within future low emission power generation. Due to the large difference in the physical properties of Hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for Dry Low NOx (DLN) Hydrogen combustion. Thus, the development of DLN combustion technologies is an essential and challenging task for the future of Hydrogen fuelled gas turbines. The DLN Micromix combustion principle for hydrogen fuel has been developed to significantly reduce NOx-emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized diffusion-type flames. The major advantages of this combustion principle are the inherent safety against flash-back and the low NOx-emissions due to a very short residence time of reactants in the flame region of the micro-flames. The Micromix Combustion technology has been already proven experimentally and numerically for pure Hydrogen fuel operation at different energy density levels. The aim of the present study is to analyze the influence of different geometry parameter variations on the flame structure and the NOx emission and to identify the most relevant design parameters, aiming to provide a physical understanding of the Micromix flame sensitivity to the burner design and identify further optimization potential of this innovative combustion technology while increasing its energy density and making it mature enough for real gas turbine application. The study reveals great optimization potential of the Micromix Combustion technology with respect to the DLN characteristics and gives insight into the impact of geometry modifications on flame structure and NOx emission. This allows to further increase the energy density of the Micromix burners and to integrate this technology in industrial gas turbines.}, language = {en} } @article{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {Automated modal parameter-based anomaly detection under varying wind excitation}, series = {Structural Health Monitoring}, volume = {15}, journal = {Structural Health Monitoring}, number = {6}, publisher = {Sage}, address = {London}, issn = {1475-9217}, doi = {10.1177/1475921716665803}, pages = {1 -- 20}, year = {2016}, abstract = {Wind-induced operational variability is one of the major challenges for structural health monitoring of slender engineering structures like aircraft wings or wind turbine blades. Damage sensitive features often show an even bigger sensitivity to operational variability. In this study a composite cantilever was subjected to multiple mass configurations, velocities and angles of attack in a controlled wind tunnel environment. A small-scale impact damage was introduced to the specimen and the structural response measurements were repeated. The proposed damage detection methodology is based on automated operational modal analysis. A novel baseline preparation procedure is described that reduces the amount of user interaction to the provision of a single consistency threshold. The procedure starts with an indeterminate number of operational modal analysis identifications from a large number of datasets and returns a complete baseline matrix of natural frequencies and damping ratios that is suitable for subsequent anomaly detection. Mahalanobis distance-based anomaly detection is then applied to successfully detect the damage under varying severities of operational variability and with various degrees of knowledge about the present operational conditions. The damage detection capabilities of the proposed methodology were found to be excellent under varying velocities and angles of attack. Damage detection was less successful under joint mass and wind variability but could be significantly improved through the provision of the currently encountered operational conditions.}, language = {en} } @article{PeloniCeriottiDachwald2016, author = {Peloni, Alessandro and Ceriotti, Matteo and Dachwald, Bernd}, title = {Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission}, series = {Journal of Guidance, Control, and Dynamics}, volume = {39}, journal = {Journal of Guidance, Control, and Dynamics}, number = {12}, publisher = {AIAA}, address = {Reston, Va.}, issn = {0731-5090}, doi = {10.2514/1.G000470}, pages = {2712 -- 2724}, year = {2016}, abstract = {The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology.}, language = {en} } @article{Finger2016, author = {Finger, Felix}, title = {Senkrechtstarter: FH-Absolvent wird f{\"u}r Transportdrohne ausgezeichnet}, series = {campushunter: das etwas andere Karrieremagazin - Wintersemester 16/17}, journal = {campushunter: das etwas andere Karrieremagazin - Wintersemester 16/17}, number = {17. Regionalausgabe Aachen}, publisher = {Campushunter Media}, address = {Heidelberg}, issn = {2196-9426}, pages = {116 -- 117}, year = {2016}, language = {de} } @article{FunkeBeckmannKeinzetal.2016, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion}, series = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016}, journal = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-4975-0}, doi = {10.1115/GT2016-56430}, pages = {12}, year = {2016}, abstract = {The Dry-Low-NOₓ (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOₓ emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOₓ emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H₂-CO) numerical analyses based on a skeletal H₂/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.}, language = {en} } @article{PeloniDachwaldCeriotti2017, author = {Peloni, Alessandro and Dachwald, Bernd and Ceriotti, Matteo}, title = {Multiple near-earth asteroid rendezvous mission: Solar-sailing options}, series = {Advances in Space Research}, journal = {Advances in Space Research}, number = {In Press, Corrected Proof}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, doi = {10.1016/j.asr.2017.10.017}, year = {2017}, language = {en} } @article{Finger2017, author = {Finger, Felix}, title = {Vergleichende Leistungs- und Nutzenbewertung von VTOL- und CTOL-UAVs}, series = {Luft- und Raumfahrt : informieren, vernetzen, f{\"o}rdern / Hrsg.: Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt}, volume = {38}, journal = {Luft- und Raumfahrt : informieren, vernetzen, f{\"o}rdern / Hrsg.: Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt}, number = {1}, issn = {0173-6264}, pages = {44 -- 47}, year = {2017}, language = {de} } @article{PetersonRoethUibel2017, author = {Peterson, Leif Arne and R{\"o}th, Thilo and Uibel, Thomas}, title = {Einsatz von Holzwerkstoffen in Fahrzeugstrukturen}, series = {Bauen mit Holz}, journal = {Bauen mit Holz}, number = {3}, publisher = {Bruderverlag}, address = {K{\"o}ln}, issn = {0005-6545}, pages = {32 -- 38}, year = {2017}, language = {de} } @article{BarnatFariaBosse2017, author = {Barnat, Miriam and Faria, Joana Abelha and Bosse, Elke}, title = {Heterogenit{\"a}t und Studierf{\"a}higkeit: Erste Ergebnisse einer L{\"a}ngsschnittbefragung}, series = {Qualit{\"a}t in der Wissenschaft: QiW ; Zeitschrift f{\"u}r Qualit{\"a}tsentwicklung in Forschung, Studium und Administration}, volume = {11}, journal = {Qualit{\"a}t in der Wissenschaft: QiW ; Zeitschrift f{\"u}r Qualit{\"a}tsentwicklung in Forschung, Studium und Administration}, number = {1}, publisher = {UVW Universit{\"a}ts-Verlag Webler}, address = {Bielefeld}, issn = {1860-3041}, pages = {17 -- 24}, year = {2017}, language = {de} } @article{FunkeKeinzKustereretal.2017, author = {Funke, Harald and Keinz, Jan and Kusterer, K. and Haj Ayed, A. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Development and Testing of a Low NOX Micromix Combustion Chamber for an Industrial Gas Turbine}, series = {International Journal of Gas Turbine, Propulsion and Power Systems}, volume = {9}, journal = {International Journal of Gas Turbine, Propulsion and Power Systems}, number = {1}, issn = {1882-5079}, doi = {10.38036/jgpp.9.1_27}, pages = {27 -- 36}, year = {2017}, abstract = {The Micromix combustion principle, based on cross-flow mixing of air and hydrogen, promises low emission applications in future gas turbines. The Micromix combustion takes place in several hundreds of miniaturized diffusion-type micro-flames. The major advantage is the inherent safety against flash-back and low NOx-emissions due to a very short residence time of reactants in the flame region. The paper gives insight into the Micromix design and scaling procedure for different energy densities and the interaction of scaling laws and key design drivers in gas turbine integration. Numerical studies, experimental testing, gas turbine integration and interface considerations are evaluated. The aerodynamic stabilization of the miniaturized flamelets and the resulting flow field, flame structure and NOx formation are analysed experimentally and numerically. The results show and confirm the successful adaption of the low NOx Micromix characteristics for a range of different nozzle sizes, energy densities and thermal power output.}, language = {de} } @article{WeberRuffStahl2017, author = {Weber, Tobias and Ruff-Stahl, Hans-Joachim K.}, title = {Advances in Composite Manufacturing of Helicopter Parts}, series = {International Journal of Aviation, Aeronautics, and Aerospace}, volume = {4}, journal = {International Journal of Aviation, Aeronautics, and Aerospace}, number = {1}, issn = {2374-6793}, doi = {10.15394/ijaaa.2017.1153}, year = {2017}, language = {en} } @article{WeberArentSteffenetal.2017, author = {Weber, Tobias and Arent, Jan-Christoph and Steffen, Lucas and Balvers, Johannes M. and Duhovic, Miro}, title = {Thermal optimization of composite autoclave molds using the shift factor approach for boundary condition estimation}, series = {Journal of Composite Materials}, volume = {51}, journal = {Journal of Composite Materials}, number = {12}, publisher = {Sage}, address = {London}, issn = {1530-793X}, doi = {10.1177/0021998317699868}, pages = {1753 -- 1767}, year = {2017}, language = {en} } @article{NeuJanserKhatibietal.2017, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {Fully Automated Operational Modal Analysis using multi-stage clustering}, series = {Mechanical Systems and Signal Processing}, volume = {Vol. 84, Part A}, journal = {Mechanical Systems and Signal Processing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0888-3270}, doi = {10.1016/j.ymssp.2016.07.031}, pages = {308 -- 323}, year = {2017}, language = {en} } @article{AyedKustererFunkeetal.2017, author = {Ayed, Anis Haj and Kusterer, Karsten and Funke, Harald and Keinz, Jan and Bohn, D.}, title = {CFD based exploration of the dry-low-NOx hydrogen micromix combustion technology at increased energy densities}, series = {Propulsion and Power Research}, volume = {6}, journal = {Propulsion and Power Research}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {2212-540X}, doi = {10.1016/j.jppr.2017.01.005}, pages = {15 -- 24}, year = {2017}, language = {en} } @article{RoethPielenWolffetal.2018, author = {R{\"o}th, Thilo and Pielen, Michael and Wolff, Klaus and L{\"u}diger, Thomas}, title = {Urbane Fahrzeugkonzepte f{\"u}r die Shared Mobility}, series = {Automobiltechnische Zeitschrift - ATZ}, volume = {120}, journal = {Automobiltechnische Zeitschrift - ATZ}, number = {1}, publisher = {Springer Vieweg}, address = {Wiesbaden}, issn = {0001-2785}, doi = {10.1007/s35148-017-0176-8}, pages = {18 -- 23}, year = {2018}, abstract = {Urbane Mobilit{\"a}tskonzepte der Zukunft erfordern neue Unternehmensformen, idealerweise aus Old Economy und New Economy, sowie eine enge Anbindung an die gesellschaftsrelevante Zukunftsforschung. F{\"u}r neue Fahrzeugkonzepte des Carsharing bedeutet dies, dass alle kostenverursachenden Faktoren erfasst und analysiert werden m{\"u}ssen. Die FH Aachen, share2drive und FEV geben einen Ausblick auf die zuk{\"u}nftige Fahrzeugklasse der Personal Public Vehicles als „Rolling Device".}, language = {de} } @article{SchirraBissonnetteBramesfeld2018, author = {Schirra, Julian and Bissonnette, William and Bramesfeld, G{\"o}tz}, title = {Wake-model effects on induced drag prediction of staggered boxwings}, series = {Aerospace}, volume = {5}, journal = {Aerospace}, number = {1}, issn = {2226-4310}, doi = {10.3390/aerospace5010014}, year = {2018}, language = {en} } @article{TekinAshikagaHorikawaetal.2018, author = {Tekin, Nurettin and Ashikaga, Mitsugu and Horikawa, Atsushi and Funke, Harald}, title = {Enhancement of fuel flexibility of industrial gas turbines by development of innovative hydrogen combustion systems}, series = {Gas for energy}, journal = {Gas for energy}, number = {2}, publisher = {Vulkan-Verlag}, address = {Essen}, pages = {4}, year = {2018}, abstract = {For fuel flexibility enhancement hydrogen represents a possible alternative gas turbine fuel within future low emission power generation, in case of hydrogen production by the use of renewable energy sources such as wind energy or biomass. Kawasaki Heavy Industries, Ltd. (KHI) has research and development projects for future hydrogen society; production of hydrogen gas, refinement and liquefaction for transportation and storage, and utilization with gas turbine / gas engine for the generation of electricity. In the development of hydrogen gas turbines, a key technology is the stable and low NOx hydrogen combustion, especially Dry Low Emission (DLE) or Dry Low NOx (DLN) hydrogen combustion. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for DLE hydrogen combustion. Thus, the development of DLE hydrogen combustion technologies is an essential and challenging task for the future of hydrogen fueled gas turbines. The DLE Micro-Mix combustion principle for hydrogen fuel has been in development for many years to significantly reduce NOx emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized "diffusion-type" flames. The major advantages of this combustion principle are the inherent safety against flashback and the low NOx-emissions due to a very short residence time of the reactants in the flame region of the micro-flames.}, language = {en} } @article{OttenWeberArent2018, author = {Otten, Dennis and Weber, Tobias and Arent, Jan-Christoph}, title = {Manufacturing Process Simulation - On Its Way to Industrial Application}, series = {International Journal of Aviation, Aeronautics, and Aerospace}, volume = {5}, journal = {International Journal of Aviation, Aeronautics, and Aerospace}, number = {2}, publisher = {Embry-Riddle Aeronautical University}, address = {Daytona Beach, Fla.}, issn = {2374-6793}, doi = {10.15394/ijaaa.2018.1217}, year = {2018}, abstract = {Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview of the capabilities of MPS in the fields of sheet metal forming and prepreg autoclave manufacturing of composite parts summarizing the resulting benefits for tooling design and manufacturing engineering. The simulation technology is explained briefly in order to show several simplification and optimization techniques for developing industrialized simulation approaches. Small case studies provide examples of an efficient application on an industrial scale.}, language = {en} } @article{FunkeBeckmannKeinzetal.2018, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-Nox-Micromix-Combustion}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {140}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {8}, publisher = {ASME}, address = {New York, NY}, issn = {0742-4795}, doi = {10.1115/1.4038882}, pages = {9 Seiten}, year = {2018}, abstract = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.}, language = {en} } @article{FingerBraunBil2018, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Impact of electric propulsion technology and mission requirements on the performance of VTOL UAVs}, series = {CEAS Aeronautical Journal}, volume = {10}, journal = {CEAS Aeronautical Journal}, number = {3}, publisher = {Springer}, issn = {1869-5582 print}, doi = {10.1007/s13272-018-0352-x}, pages = {843}, year = {2018}, abstract = {One of the engineering challenges in aviation is the design of transitioning vertical take-off and landing (VTOL) aircraft. Thrust-borne flight implies a higher mass fraction of the propulsion system, as well as much increased energy consumption in the take-off and landing phases. This mass increase is typically higher for aircraft with a separate lift propulsion system than for aircraft that use the cruise propulsion system to support a dedicated lift system. However, for a cost-benefit trade study, it is necessary to quantify the impact the VTOL requirement and propulsion configuration has on aircraft mass and size. For this reason, sizing studies are conducted. This paper explores the impact of considering a supplemental electric propulsion system for achieving hovering flight. Key variables in this study, apart from the lift system configuration, are the rotor disk loading and hover flight time, as well as the electrical systems technology level for both batteries and motors. Payload and endurance are typically used as the measures of merit for unmanned aircraft that carry electro-optical sensors, and therefore the analysis focuses on these particular parameters.}, language = {en} } @article{GoettenFingerHavermannetal.2018, author = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bill, C.}, title = {On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, journal = {Deutscher Luft- und Raumfahrtkongress 2018}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/480058}, pages = {11 S.}, year = {2018}, abstract = {The flight performance impact of three different landing gear configurations on a small, fixed-wing UAV is analyzed with a combination of RANS CFD calculations and an incremental flight performance algorithm. A standard fixed landing gear configuration is taken as a baseline, while the influence of retracting the landing gear or applying streamlined fairings is investigated. A retraction leads to a significant parasite drag reduction, while also fairings promise large savings. The increase in lift-to-drag ratio is reduced at high lift coefficients due to the influence of induced drag. All configurations are tested on three different design missions with an incremental flight performance algorithm. A trade-off study is performed using the retracted or faired landing gear's weight increase as a variable. The analysis reveals only small mission performance gains as the aerodynamic improvements are negated by weight penalties. A new workflow for decision-making is presented that allows to estimate if a change in landing gear configuration is beneficial for a small UAV.}, language = {en} } @article{CampenKowalskiLyonsetal.2019, author = {Campen, R. and Kowalski, Julia and Lyons, W.B. and Tulaczyk, S. and Dachwald, Bernd and Pettit, E. and Welch, K. A. and Mikucki, J.A.}, title = {Microbial diversity of an Antarctic subglacial community and high-resolution replicate sampling inform hydrological connectivity in a polar desert}, series = {Environmental Microbiology}, journal = {Environmental Microbiology}, number = {accepted article}, publisher = {Wiley}, address = {Weinheim}, issn = {1462-2920}, doi = {10.1111/1462-2920.14607}, year = {2019}, language = {en} } @article{SchaelAtanasyanBerdugoetal.2019, author = {Schael, S. and Atanasyan, A. and Berdugo, J. and Bretz, T. and Czupalla, Markus and Dachwald, Bernd and Doetinchem, P. von and Duranti, M. and Gast, H. and Karpinski, W. and Kirn, T. and L{\"u}belsmeyer, K. and Ma{\~n}a, C. and Marrocchesi, P.S. and Mertsch, P. and Moskalenko, I.V. and Schervan, T. and Schluse, M. and Schr{\"o}der, K.-U. and Schultz von Dratzig, A. and Senatore, C. and Spies, L. and Wakely, S.P. and Wlochal, M. and Uglietti, D. and Zimmermann, J.}, title = {AMS-100: The next generation magnetic spectrometer in space - An international science platform for physics and astrophysics at Lagrange point 2}, series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, volume = {944}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, number = {162561}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-9002}, doi = {10.1016/j.nima.2019.162561}, year = {2019}, language = {en} } @article{FingerBilBraun2019, author = {Finger, Felix and Bil, Cees and Braun, Carsten}, title = {Initial Sizing Methodology for Hybrid-Electric General Aviation Aircraft}, series = {Journal of Aircraft}, volume = {57}, journal = {Journal of Aircraft}, number = {2}, issn = {1533-3868}, doi = {10.2514/1.C035428}, pages = {245 -- 255}, year = {2019}, language = {en} } @article{FunkeBeckmannKeinzetal.2019, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {11}, journal = {Journal of Thermal Science and Engineering Applications}, number = {1}, publisher = {ASME}, address = {New York}, issn = {19485085}, doi = {10.1115/1.4041495}, pages = {011015}, year = {2019}, language = {en} } @article{ThomaRavi2019, author = {Thoma, Andreas and Ravi, Sridhar}, title = {Significance of parallel computing on the performance of Digital Image Correlation algorithms in MATLAB}, pages = {1 -- 17}, year = {2019}, abstract = {Digital Image Correlation (DIC) is a powerful tool used to evaluate displacements and deformations in a non-intrusive manner. By comparing two images, one of the undeformed reference state of a specimen and another of the deformed target state, the relative displacement between those two states is determined. DIC is well known and often used for post-processing analysis of in-plane displacements and deformation of specimen. Increasing the analysis speed to enable real-time DIC analysis will be beneficial and extend the field of use of this technique. Here we tested several combinations of the most common DIC methods in combination with different parallelization approaches in MATLAB and evaluated their performance to determine whether real-time analysis is possible with these methods. To reflect improvements in computing technology different hardware settings were also analysed. We found that implementation problems can reduce the efficiency of a theoretically superior algorithm such that it becomes practically slower than a suboptimal algorithm. The Newton-Raphson algorithm in combination with a modified Particle Swarm algorithm in parallel image computation was found to be most effective. This is contrary to theory, suggesting that the inverse-compositional Gauss-Newton algorithm is superior. As expected, the Brute Force Search algorithm is the least effective method. We also found that the correct choice of parallelization tasks is crucial to achieve improvements in computing speed. A poorly chosen parallelisation approach with high parallel overhead leads to inferior performance. Finally, irrespective of the computing mode the correct choice of combinations of integerpixel and sub-pixel search algorithms is decisive for an efficient analysis. Using currently available hardware realtime analysis at high framerates remains an aspiration.}, language = {en} } @article{WeberEnglhardArentetal.2019, author = {Weber, Tobias and Englhard, Markus and Arent, Jan-Christoph and Hausmann, Joachim}, title = {An experimental characterization of wrinkling generated during prepreg autoclave manufacturing using caul plates}, series = {Journal of Composite Materials}, volume = {53}, journal = {Journal of Composite Materials}, number = {26-27}, issn = {1530-793X}, doi = {10.1177/0021998319846556}, pages = {3757 -- 3773}, year = {2019}, language = {en} } @article{JanThimoBauerBieleetal.2019, author = {Jan Thimo, Grundmann and Bauer, Waldemar and Biele, Jens and Boden, Ralf and Ceriotti, Matteo and Cordero, Federico and Dachwald, Bernd and Dumont, Etienne and Grimm, Christian D. and Hercik, David}, title = {Capabilities of Gossamer-1 derived small spacecraft solar sails carrying Mascot-derived nanolanders for in-situ surveying of NEAs}, series = {Acta Astronautica}, volume = {156}, journal = {Acta Astronautica}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0094-5765}, doi = {10.1016/j.actaastro.2018.03.019}, pages = {330 -- 362}, year = {2019}, language = {en} } @article{LyonsMikuckiGermanetal.2019, author = {Lyons, W. Berry and Mikucki, Jill A. and German, Laura A. and Welch, Kathleen A. and Welch, Susan A. and Gardener, Christopher B. and Tulaczyk, Slawek M. and Pettit, Erin C. and Kowalski, Julia and Dachwald, Bernd}, title = {The Geochemistry of Englacial Brine from Taylor Glacier, Antarctica}, series = {Journal of Geophysical Research: Biogeosciences}, journal = {Journal of Geophysical Research: Biogeosciences}, publisher = {Wiley}, address = {Hoboken}, issn = {2169-8961}, doi = {10.1029/2018JG004411}, year = {2019}, language = {en} } @article{GoettenHavermannBraunetal.2019, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bil, Cees}, title = {RANS Simulation Validation of a Small Sensor Turret for UAVs}, series = {Journal of Aerospace Engineering}, volume = {32}, journal = {Journal of Aerospace Engineering}, number = {5}, publisher = {ASCE}, address = {New York}, issn = {1943-5525}, doi = {10.1061/(ASCE)AS.1943-5525.0001055}, pages = {Article number 04019060}, year = {2019}, abstract = {Recent Unmanned Aerial Vehicle (UAV) design procedures rely on full aircraft steady-state Reynolds-Averaged-Navier-Stokes (RANS) analyses in early design stages. Small sensor turrets are included in such simulations, even though their aerodynamic properties show highly unsteady behavior. Very little is known about the effects of this approach on the simulation outcomes of small turrets. Therefore, the flow around a model turret at a Reynolds number of 47,400 is simulated with a steady-state RANS approach and compared to experimental data. Lift, drag, and surface pressure show good agreement with the experiment. The RANS model predicts the separation location too far downstream and shows a larger recirculation region aft of the body. Both characteristic arch and horseshoe vortex structures are visualized and qualitatively match the ones found by the experiment. The Reynolds number dependence of the drag coefficient follows the trend of a sphere within a distinct range. The outcomes indicate that a steady-state RANS model of a small sensor turret is able to give results that are useful for UAV engineering purposes but might not be suited for detailed insight into flow properties.}, language = {en} } @article{FunkeBeckmannAbanteriba2019, author = {Funke, Harald and Beckmann, Nils and Abanteriba, Sylvester}, title = {An overview on dry low NOx micromix combustor development for hydrogen-rich gas turbine applications}, series = {International Journal of Hydrogen Energy}, volume = {44}, journal = {International Journal of Hydrogen Energy}, number = {13}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2019.01.161}, pages = {6978 -- 6990}, year = {2019}, language = {en} } @article{FingerGoetten2019, author = {Finger, Felix and G{\"o}tten, Falk}, title = {Neue Ans{\"a}tze f{\"u}r die Entwicklung von unbemannten Flugger{\"a}ten}, series = {Ingenieurspiegel}, volume = {2019}, journal = {Ingenieurspiegel}, number = {1}, isbn = {1868-5919}, pages = {67 -- 68}, year = {2019}, abstract = {Wie sieht das unbemannte Flugzeug von {\"U}bermorgen aus? Dieser Frage stellen sich Forscher an der Fachhochschule Aachen. Die weltweit rasant fortschreitende Entwicklung des Marktes f{\"u}r unbemannte Flugger{\"a}te (UAVs - „Unmanned Aerial Vehicles") bietet großes Potenzial f{\"u}r Wachstum und Wertsch{\"o}pfung. Unbemannte fliegende Systeme k{\"o}nnen - f{\"u}r bestimmte Anwendungsgebiete - wesentlich g{\"u}nstiger, kleiner und effizienter ausgelegt werden als bemannte L{\"o}sungen. Dabei sind sich viele Unternehmen {\"u}ber das m{\"o}gliche Potential dieser Technologie noch gar nicht bewusst.}, language = {de} } @article{SchildtBraunMarzocca2019, author = {Schildt, Ph. and Braun, Carsten and Marzocca, P.}, title = {Metric evaluating potentials of condition-monitoring approaches for hybrid electric aircraft propulsion systems}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Berlin}, issn = {1869-5590}, doi = {10.1007/s13272-019-00411-3}, pages = {1 -- 14}, year = {2019}, language = {en} } @article{GoettenHavermannBraunetal.2020, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Marino, Matthew and Bil, Cees}, title = {Airfoil drag at low-to-medium reynolds numbers: A novel estimation method}, series = {AIAA Journal}, volume = {58}, journal = {AIAA Journal}, number = {7}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-385X}, doi = {10.2514/1.J058983}, pages = {2791 -- 2805}, year = {2020}, abstract = {This paper presents a novel method for airfoil drag estimation at Reynolds numbers between 4×10⁵ and 4×10⁶. The novel method is based on a systematic study of 40 airfoils applying over 600 numerical simulations and considering natural transition. The influence of the airfoil thickness-to-chord ratio, camber, and freestream Reynolds number on both friction and pressure drag is analyzed in detail. Natural transition significantly affects drag characteristics and leads to distinct drag minima for different Reynolds numbers and thickness-to-chord ratios. The results of the systematic study are used to develop empirical correlations that can accurately predict an airfoil drag at low-lift conditions. The new approach estimates a transition location based on airfoil thickness-to-chord ratio, camber, and Reynolds number. It uses the transition location in a mixed laminar-turbulent skin-friction calculation, and corrects the skin-friction coefficient for separation effects. Pressure drag is estimated separately based on correlations of thickness-to-chord ratio, camber, and Reynolds number. The novel method shows excellent accuracy when compared with wind-tunnel measurements of multiple airfoils. It is easily integrable into existing aircraft design environments and is highly beneficial in the conceptual design stage.}, language = {en} } @article{HeinEubanksHibberdetal.2020, author = {Hein, Andreas M. and Eubanks, T. Marshall and Hibberd, Adam and Fries, Dan and Schneider, Jean and Lingam, Manasvi and Kennedy, Robert and Perakis, Nikolaos and Dachwald, Bernd and Kervella, Pierre}, title = {Interstellar Now! Missions to and sample returns from nearby interstellar objects}, publisher = {Elsevier}, address = {Amsterdam}, pages = {1 -- 8}, year = {2020}, abstract = {The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system.}, language = {en} } @article{DachwaldUlamecPostbergetal.2020, author = {Dachwald, Bernd and Ulamec, Stephan and Postberg, Frank and Sohl, Frank and Vera, Jean-Pierre de and Christoph, Waldmann and Lorenz, Ralph D. and Hellard, Hugo and Biele, Jens and Rettberg, Petra}, title = {Key technologies and instrumentation for subsurface exploration of ocean worlds}, series = {Space Science Reviews}, volume = {216}, journal = {Space Science Reviews}, number = {Art. 83}, publisher = {Springer}, address = {Dordrecht}, issn = {1572-9672}, doi = {10.1007/s11214-020-00707-5}, pages = {45}, year = {2020}, abstract = {In this chapter, the key technologies and the instrumentation required for the subsurface exploration of ocean worlds are discussed. The focus is laid on Jupiter's moon Europa and Saturn's moon Enceladus because they have the highest potential for such missions in the near future. The exploration of their oceans requires landing on the surface, penetrating the thick ice shell with an ice-penetrating probe, and probably diving with an underwater vehicle through dozens of kilometers of water to the ocean floor, to have the chance to find life, if it exists. Technologically, such missions are extremely challenging. The required key technologies include power generation, communications, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization and cleaning. Simpler mission concepts involve impactors and penetrators or - in the case of Enceladus - plume-fly-through missions.}, language = {en} } @article{GoettenFinger2020, author = {G{\"o}tten, Falk and Finger, Felix}, title = {PhoenAIX - Die modulare Transportdrohne}, series = {Ingenieurspiegel}, volume = {2020}, journal = {Ingenieurspiegel}, number = {1}, publisher = {Public Verlag}, address = {Bingen}, isbn = {1868-5919}, pages = {38 -- 40}, year = {2020}, abstract = {Die autonome, unbemannte Luftfahrt ist einer der Schl{\"u}sselsektoren f{\"u}r die Zukunft der Luftfahrt. In diesem rasant wachsenden Bereich nehmen senkrecht startende und senkrecht landende Flugzeuge (Vertical Take-Off and Landing - VTOL) einen besonderen Platz ein. Ein VTOL-Flugzeug (manchmal auch „Transitionsflugger{\"a}t" genannt) verbindet die Eigenschaft des Helikopters, {\"u}berall starten und landen zu k{\"o}nnen, mit den Geschwindigkeits-, Reichweiten und Flugdauervorteilen des Starrfl{\"u}glers. Grunds{\"a}tzlich wird die Senkrechtstart- und -landef{\"a}higkeit sowohl von zivilen als auch von milit{\"a}rischen Betreibern unbemannter Flugger{\"a}te (UAVs) gew{\"u}nscht. Trotzdem bietet der Markt nur eine geringe Anzahl von VTOL-UAVs, da qualitativ hochwertige Entw{\"u}rfe eine ausgesprochene Herausforderung in der Entwicklung darstellen. An der FH Aachen wird deshalb seit {\"u}ber 5 Jahren an der Auslegung und Analyse von solchen unbemannten VTOL Flugzeugen geforscht. Das neuste Projekt ist der Eigenentwurf einer großen, senkrechtstartenden Transportdrohne. Das „PhoenAIX" getaufte Flugger{\"a}t wird von Falk G{\"o}tten und Felix Finger im Rahmen einer EFRE-F{\"o}rderung entwickelt.}, language = {de} } @article{KreyerMuellerEsch2020, author = {Kreyer, J{\"o}rg and M{\"u}ller, Marvin and Esch, Thomas}, title = {A Calculation Methodology for Predicting Exhaust Mass Flows and Exhaust Temperature Profiles for Heavy-Duty Vehicles}, series = {SAE International Journal of Commercial Vehicles}, volume = {13}, journal = {SAE International Journal of Commercial Vehicles}, number = {2}, publisher = {SAE International}, address = {Warrendale, Pa.}, issn = {1946-3928}, doi = {10.4271/02-13-02-0009}, pages = {129 -- 143}, year = {2020}, abstract = {The predictive control of commercial vehicle energy management systems, such as vehicle thermal management or waste heat recovery (WHR) systems, are discussed on the basis of information sources from the field of environment recognition and in combination with the determination of the vehicle system condition. In this article, a mathematical method for predicting the exhaust gas mass flow and the exhaust gas temperature is presented based on driving data of a heavy-duty vehicle. The prediction refers to the conditions of the exhaust gas at the inlet of the exhaust gas recirculation (EGR) cooler and at the outlet of the exhaust gas aftertreatment system (EAT). The heavy-duty vehicle was operated on the motorway to investigate the characteristic operational profile. In addition to the use of road gradient profile data, an evaluation of the continuously recorded distance signal, which represents the distance between the test vehicle and the road user ahead, is included in the prediction model. Using a Fourier analysis, the trajectory of the vehicle speed is determined for a defined prediction horizon. To verify the method, a holistic simulation model consisting of several hierarchically structured submodels has been developed. A map-based submodel of a combustion engine is used to determine the EGR and EAT exhaust gas mass flows and exhaust gas temperature profiles. All simulation results are validated on the basis of the recorded vehicle and environmental data. Deviations from the predicted values are analyzed and discussed.}, language = {en} } @article{GazdaMaurischat2020, author = {Gazda, Quentin and Maurischat, Andreas}, title = {Special functions and Gauss-Thakur sums in higher rank and dimension}, publisher = {De Gruyter}, address = {Berlin}, pages = {26 Seiten}, year = {2020}, language = {en} }